Such pressure maintenance-type components are known to the prior art in diverse forms of embodiments, in particular as integral components of directional control valves. For example, EP 1 500 825 A2 discloses a pressure maintenance valve with a valve slide that is movably guided in a longitudinal direction in a valve housing and that has a control part for controlling a fluid-conducting connection between at least two fluid connection points accommodated in the valve housing. The control part has at least one pocket-shaped recess, at least part of which is bordered by a fluid-guiding surface extending between at least two vertices of the recess and extending with an initially increasing and then constant slope from one vertex to the other vertex. The other vertex, which is arranged at the exit of the pocket-shaped recess, borders the edge or corner point of a right angle as a transition between the fluid-guiding surface and a collar surface of the valve slide or control slide. The collar surface extends perpendicular to the fluid-guiding surface.
The disadvantage with such pressure maintenance valves arises in that starting from the zero stroke, the progression of the active standard cross section increases quite abruptly over the opening stroke and has at least one kink in the further progression. Due to this progression of the standard cross section over the opening stroke, the control accuracy and the stability of the prior art pressure maintenance valves need improvement to increase the precision of the fluid control.
Because the prior art directional control valves with upstream or downstream pressure maintenance components must frequently fulfill a load-holding function, of which the geometric configuration is typically embodied by a circumferential vertical edge, effective compensation of the flow forces is thus complicated.